How to set the maxAllowedContentLength to 500MB while running on IIS7?

According to MSDN maxAllowedContentLength has type uint, its maximum value is 4,294,967,295 bytes = 3,99 gb

So it should work fine.

See also Request Limits article. Does IIS return one of these errors when the appropriate section is not configured at all?

See also: Maximum request length exceeded

The limit of requests in .Net can be configured from two properties together:

First

• Web.Config/system.web/httpRuntime/maxRequestLength
• Unit of measurement: kilobytes
• Default value 4096 KB (4 MB)
• Max. value 2147483647 KB (2 TB)

Second

• Web.Config/system.webServer/security/requestFiltering/requestLimits/maxAllowedContentLength (in bytes)
• Unit of measurement: bytes
• Default value 30000000 bytes (28.6 MB)
• Max. value 4294967295 bytes (4 GB)

References:

• http://www.whatsabyte.com/P1/byteconverter.htm
• https://www.iis.net/configreference/system.webserver/security/requestfiltering/requestlimits

Example:

<location path="upl">
   <system.web>
     <!--The default size is 4096 kilobytes (4 MB). MaxValue is 2147483647 KB (2 TB)-->
     <!-- 100 MB in kilobytes -->
     <httpRuntime maxRequestLength="102400" />
   </system.web>
   <system.webServer>
     <security>
       <requestFiltering>          
         <!--The default size is 30000000 bytes (28.6 MB). MaxValue is 4294967295 bytes (4 GB)-->
         <!-- 100 MB in bytes -->
         <requestLimits maxAllowedContentLength="104857600" />
       </requestFiltering>
     </security>
   </system.webServer>
 </location>

IIS v10 (but this should be the same also for IIS 7.x)

Quick addition for people which are looking for respective max values

Max for maxAllowedContentLength is: UInt32.MaxValue 🡒 4294967295 bytes : ~4GB

Max for maxRequestLength is: Int32.MaxValue 🡒 2147483647 bytes : ~2GB

web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.web>
    <!-- ~ 2GB -->
    <httpRuntime maxRequestLength="2147483647" />
  </system.web>
  <system.webServer>
    <security>
      <requestFiltering>
        <!-- ~ 4GB -->
        <requestLimits maxAllowedContentLength="4294967295" />
      </requestFiltering>
    </security>
  </system.webServer>
</configuration>